…light.proto comments
When reading the Flight.proto comments, I found some typos and grammar issue. This PR is simple fix to the comments.
Author: m.wang <m.wang@alibaba-inc.com>
Closes#2965 from wangmiao1981/typo and squashes the following commits:
ac6db4b <m.wang> fix typo and grammar of Flight.proto

The metadata currently uses Google's flatbuffers library for serializing a
couple related pieces of information:

Schemas for tables or record (row) batches. This contains the logical types,
field names, and other metadata. Schemas do not contain any information about
actual data.

Data headers for record (row) batches. These must correspond to a known
schema, and enable a system to send and receive Arrow row batches in a form
that can be precisely disassembled or reconstructed.

Arrow Format Maturity and Stability

We have made significant progress hardening the Arrow in-memory format and
Flatbuffer metadata since the project started in February 2016. We have
integration tests which verify binary compatibility between the Java and C++
implementations, for example.

Major versions may still include breaking changes to the memory format or
metadata, so it is recommended to use the same released version of all
libraries in your applications for maximum compatibility. Data stored in the
Arrow IPC formats should not be used for long term storage.